innova 3721 battery and charging system monitor

In conclusion, this is a useful tool and I do not like to have it plugged in all the time but if you doubt your battery's health plug it in and get some readings. In this case, you will see readings of less than 13V while the car is running but that will be short lived because the battery will not be fully charged for long and the voltage should jump back up to start charging it again. Having said that, contemporary charging systems may monitor the amount of amperage that the battery is drawing and stop charging the battery because it is fully charged. You should get a reading close or a little more than 14V but generally readings between 13.5V and 15.0V while the car is running are good and this means that your car is charging the battery. So to see if your car's charging system works well, plug in this meter and start your car. However, you should not see the voltage jumping up and down more than a few tenths of a volt constantly. Because of this, when you take voltage readings while the car is running, you may see the voltage move up and down and seem unstable. A typical alternator will provide 14V to 15V while the car is running but alternators are not like generators and they need to keep adjusting the output voltage with a circuit called the regulator because the engine revs are rarely constant. To do so, it has to provide higher voltage levels than the battery itself so the battery can be charged. When your car is running, the alternator is charging the battery. The truth is that the best indicator of your battery's health is how fast the battery discharges under load but you will not know how much 'load' is on your battery while you are taking the voltage readings so it is hard to explain this in a review.Ĭhecking your charging system (alternator) health: You should not expect that you will see the 'fully charged, no load' reading of 13V because unless you have an antique, your car uses battery power even when the ignition is off for many things including waiting for you to press the buttons on your keyfob or turn on the dome light when you come close to your car door with keyless entry. The reading should not be less than 12V and the higher it is the better the battery is doing. Based on this, if you want to see how is the health of your battery, you should get in the car after the car has been off for more than 12 hours, turn on the ignition (do not start the car) and take a reading. Most cars will not crank 'happily' if the battery voltage is less than 12V before you start cranking. If you plug this meter to your receptacle and turn the ignition key to on (engine not running) and you get a reading less than 12V, your battery needs to be charged soon. A car battery under normal load (not cranking the engine but have the ignition key turned to on without the car running) should not give you a reading of less than 12V. If you do not want me to bore you with details, all you need to do is plug this in and get 12 to 13V while the car is not running and get 13.5V or more while the car is running.Ī lead acid car battery is typically 12V but a healthy fully charged 12V battery that has no load connected to it will give you a reading of 13V or a little over that.

Once you understand the voltage numbers that you see you will find this to be a very useful tool and if you are willing to read further, I will attempt to explain the voltage readings you will get. Now, let me say that the bar graph to the right of the voltage reading and the symbols above that are also useless and pointless. I now have a different car that I purchased a couple of years ago and last year the dealership replaced the battery under warranty but this winter I started having battery problems again and so I dusted off this meter and plugged it in to try and get a better picture of what is going on with this battery.įirst, let me say that all that matters is the voltage reading and the green, yellow and red led indicators on it are useless and pointless. I purchased this battery voltage meter back in 2013 when a car I had was giving me hard time with the battery.

Innova 3721 battery and charging system monitor